The Red Queen Hypothesis

Cuckoo birds take advantage of Warblers by parasitizing their nest and fooling the parents into thinking they're providing for their own (surprisingly large) chicks. To defend against this behavior, Warblers are evolving to begin to recognize Cuckoo bird eggs, while the Cuckoos are co-evolving to produce eggs that look more and more similar to the Warbler's.

The Red Queen refers to an evolutionary hypothesis proposed by Leigh Van Valen in 1973. In an evolutionary arms race, competing species will co-evolve just as quickly as needed to stay put in the ecological niche it currently holds in the ecosystem. In other words, no species ever truly ‘progresses’ or gets ahead, as it’s all relative.

The hypothesis was named for a scene in Lewis Carroll’s Through the Looking-Glass, in which the Red Queen races with Alice:

“Well, in our country,” said Alice, still panting a little, “you’d generally get to somewhere else — if you run very fast for a long time, as we’ve been doing.”

“A slow sort of country!” said the Queen. “Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!”

Also, I have red hair and I’m a Queen.

The hypothesis can apply to evolutionary psychology, as well. Some psychologists believe that men and women are in an evolutionary arms race, co-evolving to 'compete' in the sex game. While men are evolving to detect fertility signals in women (an adaptive trait for males), females are co-evolving to keep their fertility hidden (an adaptive trait for females). It's in a male's best interest to sense out which females are ovulating, to take advantage of a woman's prime-time for conception. But it's in a woman's best interest to keep her fertility hidden, otherwise males would be hounding us around our 2-day ovulatory phase, and we'd be fighting them off with sticks left and right (thereby decreasing our ability to discriminate in mates). This is a trait human females have evolved, but some primates, like Bonobos, can't hide their fertility phase. These female monkeys exhibit a fleshy pink swelling when they're ovulating, increasing males' mate-guarding behavior during this time. Simon Baker hypothesized that females are better off hiding their fertility so that they can discreetly mate with a male of higher genetic quality during their fertile phase, while still keeping the sugar-daddy around for resources (a cuckolding scheme similar to the Cuckoo's above). For more information, I'd highly recommend Baker's book, Sperm Wars.